The present invention relates to spherical hinges for hinging portions of an orthotic shell or brace that is used to stabilize a body anatomical joint. As shown, a foot support portion and a leg shell portion are hinged together. The spherical hinge accommodates some misalignment of hinge axes on opposite sides of a human limb joint so the assembly of two portions to obtain a freely movable orthosis is much easier.
The leg and foot shell portions of an ankle orthosis have long been hinged together with simple, single axis, pinned lap joint type hinges or with flexure units, such as that shown in U.S. Pat. No. 5,826,304. The flexure unit fills a distinct purpose, but in certain instances, it is orthopedically desirable to have a way to adjust the angle at which free ankle motion is stopped. This may be advantageous to accommodate changes in a patient's condition or to search out the orthotic control conditions which optimize gait.
Orthopedic braces are typically custom fabricated, one at a time by hand. In such fabrication circumstances, the ability to mount the hinges without precise alignment, and without increasing binding, stress, and conditions that cause a lot of wear, means that the finished orthosis can be fabricated at a considerably lower labor cost. Also, the ankle joints not only will function better but will last longer.
It is often the case that people who have orthopedic impairments involving one or more of the limbs can be aided by an orthosis (orthopedic brace). When an orthosis crosses a skeletal joint, for instance the ankle, as shown herein, or the knee, wrist, or elbow, there is usually a need to incorporate a set of hinge components (one on each side of the limb) into the structure of the orthosis.
When the orthosis must provide significant stabilization, deformity correcting, moments to the limb, the orthosis includes hinging components on both the medial and lateral aspects of the orthosis structure. The medial and lateral aspects of the orthosis structure desirably must pivot on an axis in line with each other and the axis of the anatomical joint in order to be comfortable, safe and cosmetic as well as provide orthopedic support.
Most limb orthosis are custom fabricated and fit to the individual user. The choice and proper incorporation of hinging components is an important aspect of that custom design and manual fabrication process. The orthotic industry does make use of some flexure type components that automatically achieve neutral axis alignment or co-alignment, because of the design. However, the flexure joints do not include an intrinsic, adjustable motion stop, which is sometimes needed. An example of such a device is shown in the previously mentioned U.S. Pat. No. 5,826,304.
Substantially all non-flexure joint components are of a pinned lap or clevis type, constrained by close tolerances to pivot about a single axis or a predetermined series of parallel axes. The pivoting parts “bind” if the medial joint component is not accurately co-aligned with the lateral joint component. In other words, the joint components on opposite sides of the actual skeletal or anatomical joint being supported must align. “Binding” due to misalignment causes higher rates of wear in the orthotic joints and hastens failure, and such binding from inadequate co-alignment can also cause distortion and extra stresses on other parts of the orthosis structure thus will produce unintended extra loads and constraints on the user's anatomy.
Those and other reasons result in the need for a great deal of care, as well as a great deal of time for fabrication to ensure co-alignment of the medial and lateral hinge or joint components. Orthotic design in recent years has resulted in considerable use of plastic shell-type structures, which are lighter and can be made to fit better. However, the plastic shells flex and bend as they come under bearing loads during use in ways that can cause joints to bind, even if the original co-alignment was perfect. In other words, in use, the joints built into plastic shell-type structures can change positions and alignment during gait.
Precise co-alignment of ankle and knee joints usually requires the use of special fixtures during fabrication. The fixtures bolt onto the joints to hold the medial and lateral joint or hinge components so that their axes of rotation coincide (co-alignment) throughout the fabrication process, to the completion of the process. The fabrication process involves hand bending and shaping of medial and lateral longitudinal bars that extend upward and downward from the joints. The bars are contoured to follow a unique pattern or plaster mold of a patient's leg. Those bars must be attached firmly to metal and/or plastic structural components, such as calf bands, thigh bands, and/or the plastic shells above and below the joint. To accomplish all that bending, shaping, and rigid structural integration, while at the same time maintaining joint co-alignment of the joint heads or components requires immense skill, care, and time. Compromises are made, which sacrifice precision of co-alignment or close fit.
Some orthoses incorporating knee joints have an additional co-alignment challenge. Bale type knee joint components incorporate a rigid semi-circular posterior linkage or bale, between the medial and lateral joint locking mechanisms. These locking mechanisms can be cams or tooth-type locks for locking the joint. This locking is to ensure there will not be any unwanted movement, or release of the joint at an inappropriate time. It is clear that the medial and lateral joint components then should lock and unlock in unison. Binding caused by inadequate co-alignment and/or by structural flexing will then also lead to wear, failure, and unreliable function of a walk enabling mechanism. Orthoses that incorporate a rigid bale lock also benefit from the present invention forming means for hinging the bale.
Co-alignment requirements also complicate the work of the orthotic technician when the orthosis must be repaired or modified, as may be necessary to accommodate changes in the patient's weight or orthopedic conditions. It should be noted that the Motloch-Fillauer ankle joint sold by Fillauer, Inc. of Chattanooga, Tenn., U.S.A. provides ankle joint pairs in a fabrication kit that includes attachment rod end spherical joints, but these joints have a problem with loads that are incurred because of the mountings. Also, they do not incorporate a means to limit/stop motion.